By way of illustration only, and not by way of limitation, the following are examples of authentication or identification conforming with the requirements of this rule:....

(5) Voice identification. Identification of a voice, whether heard firsthand or through mechanical or electronic transmission or recording, by opinion based upon hearing the voice at any time under circumstances connecting it with the alleged speaker.

So, how well must a witness know a voice before he can authenticate it consistent with Rule 901(b)(5)? According to the recent opinion of the Tenth Circuit in United States v. McDaniel, 2011 WL 4396976 (10th Cir. 2011), the answer is "not very."

Keith McDaniel was charged, along with twenty-three other individuals, with one count of conspiracy to manufacture, possess with intent to distribute, and to distribute fifty grams or more of cocaine base and to possess with intent to distribute and to distribute five kilograms or more of cocaine....At trial, the district court admitted into evidence multiple recorded telephone conversations between the conspirators which investigating officers had intercepted through wiretaps. Seven of these conversations involved Mr. McDaniel.

After he was convicted, McDaniel appealed, claiming that the prosecution failed to properly authenticate his voice on the telephone conversations. The prosecution authenticated McDaniel's voice through the testimony of Officer Eric Jones:

[OFFICER JONES]: I have spoken with Mr. McDaniel, as well as Mr. McDaniel, for instance, is one that we didn't positively identify until almost the end of our intercepts, and towards the end of the investigation we had an idea that it was him. We just didn't—we couldn't positively say initially that it was him until other aspects kind of came into play through surveillance and some other incidences later.

[PROSECUTOR]: As a result of talking to him and conducting surveillance, you're able to identify phone calls associated or between [codefendant] Monterial Wesley and Mr. McDaniel?

Officer Jones's testimony was not specific enough to establish minimal familiarity because it is unclear when Officer Jones and Mr. McDaniel spoke, for how long they spoke, where they spoke, or how much Mr. McDaniel said during their conversation. Indeed, Mr. McDaniel asserts that "[f]or all that can be gleaned from Officer Jones's testimony, it may have been an entirely one-sided conversation, with Mr. McDaniel saying virtually nothing."

The Tenth Circuit disagreed, concluding that

Rule 901 only requires that the witness have heard the voice "at any time under circumstances connecting it with the alleged speaker." Here, Officer Jones testified that he had "spoken with Mr. McDaniel," and through "surveillance and some other incidences later," he was able to identify Mr. McDaniel's voice on the recordings....

We are satisfied that the district court did not abuse its discretion in ruling that the admission of the intercepted calls was supported by sufficient evidence to satisfy Rule 901.